Module for supplying hydrogen to a fuel mini-cell with sequential control of pyrotechnic elements

ABSTRACT

The module is designed for supplying hydrogen to a fuel mini-cell, wherein hydrogen is gradually released by combustion of elements made of pyrotechnic material, after ignition. A device for sequential control of ignition of the pyrotechnic elements comprises a circuit controlling an electrical or light energy source which supplies an ignition control signal causing energy to be applied to the input of a series of connecting means, respectively associated with each of the pyrotechnic elements. A single pyrotechnic element is connected to the energy source at any one time, the elements preceding it having already been used. The connecting means can be sensitive to temperature or to pressure.

BACKGROUND OF THE INVENTION

The invention relates to a module for supplying hydrogen to a fuelmini-cell with sequential control of pyrotechnic elements.

STATE OF THE TECHNIQUE

Supplying a portable apparatus by means of a fuel mini-cell has beenproposed by the Applicant in Patent application PCT/FR01/04092 (claimingthe priority of French Patent application no. 0016941). This documentdescribes a module, for example in the form of a card in credit cardformat, in which hydrogen is gradually released according to the energyrequirement by combustion of bodies made of solid pyrotechnic material.Each solid body, made of pyrotechnic material, decomposable bycombustion, is associated with an ignition device which causescombustion of the associated body and release of hydrogen.

The above-mentioned document gives few details on how the ignitiondevices are controlled. It does however stipulate that control isadvantageously achieved electronically and uses means for addressingignition means. This implies that an electronic circuit, to which anaddress is assigned, has to be associated with each pyrotechnic element.Such a system is both complex and costly.

The addressing provided for in the above-mentioned document could beeliminated and each ignition device be controlled separately from acentralised electronic circuit connected by hardwired connections toeach ignition device. Such an arrangement would present the drawback ofrequiring a large number of electrical connections. In addition, theseconnections would have to run inside a tight enclosure, whichcomplicates achievement of the device and increases the cost thereof.

OBJECT OF THE INVENTION

The object of the invention is to achieve a module for supplyinghydrogen to a fuel mini-cell with sequential control of pyrotechnicelements not presenting these drawbacks, i.e. that is at the same timesimple to achieve, of compact size and inexpensive.

According to the invention, this object is achieved by a moduleaccording to the appended claims, and more particularly by a modulewhich comprises means for triggering and controlling gradual release ofhydrogen in a fuel mini-cell, the hydrogen being supplied, afterignition of the latter, by combustion of a plurality of pyrotechnicelements integrated in the module, said means comprising an energysource and a device for sequential control of ignition of thepyrotechnic elements comprising means for selectively connecting theenergy source to an ignition element of each of the pyrotechnicelements, the connecting means comprising means for connecting a singleignition element associated with a predetermined pyrotechnic element tothe energy source during a preset ignition time, and for automaticallypreparing connection of another pyrotechnic element to the energy sourceafter the ignition time.

According to a preferred embodiment, the connecting means comprise meanssensitive to temperature or pressure to prepare connection of anignition element of another pyrotechnic element to the energy source.

According to a first development of the invention, the energy sourcebeing an electrical energy source, the connecting means comprise aninput terminal, and means for connecting the input terminal to theenergy source during each ignition period, the input terminal being, atany given time, connected to an ignition element of a single pyrotechnicelement, combustion of said pyrotechnic element actuating, after saidignition period, connecting means sensitive to temperature or pressureautomatically causing connection of the input terminal to an ignitionelement of another pyrotechnic element.

According to a preferred embodiment, the ignition elements are heatingfilaments and, in the ignition position, the heating filament concernedis connected to the terminals of the electrical energy source, theconnecting means sensitive to temperature or pressure constitutingnormally open switches arranged between two adjacent heating filaments,a heating filament being automatically cut off during or at the end ofits ignition period.

According to a second development of the invention, the energy source isa light energy source and the connecting means comprise a plurality ofsmall mirrors arranged successively on the initial path of a light beamemitted by the light energy source, each mirror being associated with acorresponding pyrotechnic element, a light beam emitted by the lightenergy source being reflected by the first mirror encountered on itspath, in the direction of the corresponding pyrotechnic element, so asto cause ignition of the latter during an ignition period, the mirrorbeing removed from said path after the ignition period so that asubsequent light beam reaches the next mirror.

According to an alternative embodiment, the mirror can be deformed ordestroyed by the thermal energy received, after ignition of theassociated pyrotechnic element. This thermal energy can be released bycombustion of the associated pyrotechnic element and/or be at leastpartly supplied by the light beam.

According to another alternative embodiment, each mirror is arranged ona support that is deformed when the temperature reaches a preset value.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features will become more clearly apparent from thefollowing description of particular embodiments of the invention givenas non-restrictive examples only and represented in the accompanyingdrawings in which:

FIG. 1 represents, in schematic form, an electronic apparatus comprisinga fuel mini-cell in which the invention can be implemented.

FIGS. 2 and 3 illustrate, in schematic form, different embodiments of acontrol device of a module according to the invention.

FIGS. 4 to 6 represents a first embodiment of a temperature-sensitiveswitch of a control device according to FIG. 3, respectively in the openposition in a side view (FIG. 4) and a top view (FIG. 5), and in theclosed position in a side view (FIG. 6).

FIGS. 7 and 8 represent a second embodiment of a temperature-sensitiveswitch respectively in the open and closed position.

FIG. 9 illustrates a particular embodiment of a control device accordingto FIG. 3.

FIG. 10 represents a particular embodiment of a pressure-sensitiveswitch of a control device according to FIG. 3.

FIG. 11 represents another particular embodiment of a control device ofa module according to the invention in which the energy source is alaser.

FIG. 12 illustrates an alternative embodiment of mirror supports of adevice according to FIG. 11.

FIGS. 13 and 14 illustrate signals S₁ and S₂ respectively representativeof ignition command and of the combustion time of a pyrotechnic elementignited in a module according to the invention.

FIGS. 15 and 16 illustrate a particular embodiment of a device accordingto FIG. 11, respectively in front view and in side view.

FIGS. 17 and 18 illustrate an alternative embodiment of mirror supportsof a device according to FIGS. 15 and 16, respectively in perspectiveand in cross-section along A-A.

FIGS. 19 and 20 illustrate another alternative embodiment of mirrorsupports of a device according to FIGS. 15 and 16, using a shape memoryalloy, respectively in the first and second positions.

DESCRIPTION OF PARTICULAR EMBODIMENTS

The device represented in schematic form in FIG. 1 comprises a fuelmini-cell which comprises a first electrode 2 in contact with a hydrogenexpansion chamber 3. A second electrode 4 is in contact with an air flowchamber 5 and an electrolyte 6 is inserted between the first and secondelectrodes.

In this fuel mini-cell, hydrogen is gradually released according to theenergy demand by combustion of solid bodies 7 made of pyrotechnicmaterial situated in a central compartment 8. Each body 7, made ofpyrotechnic material decomposable by combustion, is associated with anignition device 9 (for example an electrical resistor) designed to causecombustion of the associated body 7. In case of hydrogen being required,a control circuit 10 commands ignition of a solid body 7 made ofpyrotechnic material, that has not yet been used.

The set of bodies 7 and associated ignition devices 9 are preferablyachieved in the form of an interchangeable module, for example ofconventional credit or smart card type format, thus enabling theassembly to be changed when all the bodies 7 have been used.

The invention, which applies to control of pyrotechnic elementsintegrated in a hydrogen supply module, can be used in particular tocontrol ignition of the solid bodies 7 made of pyrotechnic material ofthe device 1 according to FIG. 1.

The device for sequential control of pyrotechnic elements E_(i), withi=1 to n, comprises (FIG. 2) an energy source 11 designed to beselectively connected to an ignition means of each of the pyrotechnicelements E_(i).

In FIG. 2, two-position changeover switches 12 connected in seriesbetween the energy source 11 and the last pyrotechnic element E_(n) areassociated with each pyrotechnic element E_(i). In a first position, achangeover switch 12 connects the associated pyrotechnic element E_(i)to its input terminal. In a second position, it connects the inputterminal of the changeover switch 12 associated with the nextpyrotechnic element E_(i+1) to its input terminal. A single pyrotechnicelement is connected to the energy source at any one time.

In FIG. 2, only the changeover switch associated with the element E₁ isin the second position, all the other changeover switches being in thefirst position. Thus, only the element E₂ is connected to the energysource 11. The element E₁ which precedes it has already been used, whichis represented schematically in FIG. 2 by a cross over the element E₁.The control device comprises a circuit 13 controlling the energy source11, which supplies an ignition command signal S₁ (FIG. 13) causingenergy from the energy source 11 to be applied, during a preset ignitionperiod (t₀-t₁) of a few milliseconds, to the input of the series ofchangeover switches 12.

In the configuration represented in FIG. 2, application of an ignitionsignal S₁ causes ignition of the element E₂, which is the only oneconnected to the energy source. This ignition first causes combustion ofthe element E₂ during a combustion time comprised between times t₂ andt₃ (FIG. 14). The time t₂ is comprised in the ignition period (t₀-t₁),combustion continuing after the ignition period until the time t₃.

A changeover switch 12 moves from the first to the second position afterthe ignition period of the corresponding element E_(i), thusautomatically preparing connection of the next pyrotechnic elementE_(i+1) to the energy source 11.

In a preferred embodiment, the changeover switches 12 are sensitive totemperature or pressure, i.e. they switch from the first to the secondposition when their temperature or pressure exceeds a preset value. Eachchangeover switch 12 is situated near to the associated pyrotechnicelement so that combustion of the latter causes a sufficient temperatureor pressure rise to make the changeover switch concerned, and only thelatter, switch from the first to the second position between the time t₁corresponding to the end of the ignition period and the time t₃corresponding to the end of combustion.

The control circuit 13 thus triggers, when necessary, combustion of apyrotechnic element E_(i) and of this element only. Combustion of thiselement modifies the state of the changeover switch 12 situated betweenthis element E_(i) and the next element E_(i+1) so that subsequentactivation of the control circuit triggers combustion of the nextelement and of the latter only. The device thus sequentially causes, ondemand, successive combustion of the pyrotechnic elements of the modulein which they are integrated.

In the particular embodiment of FIG. 3, the energy source is anelectrical energy source, for example a disposable or storage battery14. A normally open switch 15 is connected between the battery 14 and aninput terminal 16. The switch 15 is closed by the control circuit 13during the ignition periods. The ignition elements of the pyrotechnicelements E_(i) are formed by heating filaments 17 associated with eachof the pyrotechnic elements. All the filaments 17 are continuouslyconnected to one of the terminals of the battery. At a given time, asingle heating filament 17 is connected to the input terminal 16. Thus,in the ignition position, one and only one heating filament 17 isconnected in parallel with the battery 14. Connection of a heatingfilament 17 to the input terminal 16 is performed by means of asuccession of switches 18 each arranged between two adjacent heatingfilaments and connected in series between the input terminal and theheating filament associated with the last pyrotechnic element E_(n). Theheating filament associated with the first pyrotechnic element E₁ isconnected directly to the input terminal 16 whereas the heating filamentassociated with a pyrotechnic element E_(i) is connected to the inputterminal via the switches 18 associated with the pyrotechnic elementsE_(i) to E_(i−1) preceding it. The normally open switches 18 are closedafter the ignition period of the associated pyrotechnic element, thusautomatically causing connection of the input terminal 16 to the heatingelement associated with the next pyrotechnic element.

The switches 18 are sensitive to temperature or pressure and switch fromthe open position to the closed position when their temperature orpressure exceeds a preset value. Each switch 18 is situated near to theassociated pyrotechnic element so that combustion of the latter causes asufficient temperature or pressure increase to make the switchconcerned, and only the latter, switch from the open position to theclosed position between the time t₁ corresponding to the end of theignition period and the time t₃ corresponding to the end of combustion.

To avoid simultaneous parallel connection of several heating elements 17at the terminals of the battery 14, a heating element 17 isautomatically cut off during or at the end of its ignition period. Thiscut-off of the filament can be caused by its melting at the temperatureto which it is heated either by Joule effect or by combustion of thepyrotechnic element.

The material, positioning and dimensions of the heating elements 17,pyrotechnic elements E_(i) and switches 18 are chosen in such a way thatparallel connection of a heating filament with the battery 14 during itsignition suffices to cause combustion of the associated pyrotechnicelement and, after the ignition period, to cause closing of theassociated switch 18 and cut-off of the heating filament involved, thusautomatically preparing connection of the next heating filament to theenergy source.

The heating filaments 17 can be made from a large number of resistivematerials. For non-restrictive example purposes, they can be made fromnickel-base (Ni), chromium-base (Cr), tantalum-base (Ta) or an alloy ofthese metals. In a preferred embodiment, the value of the resistanceshould advantageously be chosen so that the power dissipated in thefilament is sufficient to cause breaking thereof, like a fuse, at thesame time as it triggers ignition.

FIGS. 4 to 8 illustrate two particular embodiments of atemperature-sensitive switch. These embodiments use state-of-the-arttechniques in achieving electrical connections in integrated circuits,in particular techniques referred to as the Flip chip type.

In the embodiment of FIGS. 4 to 6, two electrically conducting tracks 19formed on an insulating support 20 are designed to be connected ordisconnected by a temperature-sensitive switch 18. The two tracks arenormally separated by a gap of a few micrometers (open position of theswitch). Each track is provided at its end with a wettable surface 21,for example formed by a thin film of gold. A material with a low meltingpoint, preferably indium, tin or a tin and lead alloy, that deforms whenthe temperature reaches a preset value, is deposited in the form of aflat wafer 22 on the end of each track 19 so as to cover the wettablesurface 21 and an adjacent part of the track. The two wafers 22 areseparated by the same gap as the tracks 19 in the open position of theswitch. When the temperature reaches a sufficient value, it causesmelting of the wafer. In liquid state, the superficial tension forcesmodify the shape of the wafers. As the surfaces 21 are covered by awettable material for the material constituting the wafers, pellets formon the wettable surfaces 21. The volume of the pellets 23 issufficiently large for the pellets to join to form a single droplet 24then electrically connecting the tracks 19 in definitive manner (closedposition of the switch). The wafers 22 can be of rectangular, circularor oval shape.

In the alternative embodiment represented in FIGS. 7 and 8, the tracks19 achieved on the support 20 are arranged facing a wafer 27. The wafer27 lies on a wettable surface 28 arranged centrally with respect tonon-wettable surfaces 29 formed on a component 30. The wafer 27,preferably of circular shape, can be arranged on a central metal stud 28surrounded by a ring 29 made of non-wettable material, for exampleformed by a layer of silicon dioxide (SiO₂). In the open position of theswitch, there is no contact between the wafer 27 and the tracks 19. Thetemperature rise causes the wafer to melt, the material of the waferthen being deformed and concentrated on the wettable surface 28, finallyforming a pellet 31 coming into contact with the end of the two tracks19 and thus establishing an electrical connection between the tracks(closed position of the switch).

FIG. 9 illustrates an embodiment of a control device according to FIG.3, achieved by planar technique using switches of the type described inFIGS. 4 to 6. The substrate 20 bears both the tracks 19 at the endswhereof the wafers 22 are deposited, and also the heating filaments 17and pyrotechnic elements. A very compact embodiment is thus obtainedwherein the moment of closing of the switches caused by melting of thewafers 22 can be adjusted by the choice of the distance d separating thepyrotechnic elements and the wafers 22. The tracks 19 can advantageouslyextend underneath the pyrotechnic elements E_(i) so as to adjust theheat exchange by conduction between the wafers 22 and the pyrotechnicelements.

In the embodiment represented in FIG. 10, the switches 18 (FIG. 3) arepressure-sensitive. Combustion of a pyrotechnic element E_(i) arrangedabove a heating filament 17 generates gas whose pressure is used to movea flexible membrane used to close the switch. In FIG. 10, the flexiblemembrane 25 bears two electrically conducting tracks 26 whose ends areseparated. When the pressure generated by the combustion gases of theassociated pyrotechnic element is sufficient, a force f deforms themembrane 25 which moves upwards. The ends of the tracks 26 then comeinto contact with a metallic stud 40 which thus ensures the continuitybetween the two tracks and performs closing of the switch concerned.This type of embodiment is well suited to sequential control ofmicro-valves belonging to micro-fluidic devices associated with anelectronic module containing a device according to the invention.

The invention is not limited to the use of an electrical energy source.In the particular embodiment of FIG. 11, the energy source is a lightenergy source, for example a laser 32. Ignition of a pyrotechnic elementE_(i) is then caused by a light beam F emitted by the laser 32 under thecontrol of the control circuit 13, during the ignition period t₀-t₁ andreaching the pyrotechnic element concerned and only this element.

Connection between the laser and the pyrotechnic elements is achieved bymeans of small mirrors 33 associated with each of the pyrotechnicelements. The mirrors 33 are arranged behind one another on the initialpath of a light beam F emitted by the laser 32. Thus, in FIG. 11, thelight beam F emitted by the laser being horizontal, all the mirrors 33are arranged on a single horizontal line. When the light beam F emittedby the laser reaches the first mirror encountered on its path, thismirror reflects in the direction of the associated pyrotechnic elementE₂, causing ignition of the latter.

After the ignition period, the mirror is removed from the initial pathof the light beam F emitted by the laser. This is preferably achieved bydeformation or destruction of the mirror by the thermal energy received,after the associated pyrotechnic element has been ignited. The mirror 33is preferably formed by a thin reflecting layer, of 500 to 600 Angstromsfor example, which resists during the time necessary for ignition of thecorresponding pyrotechnic element and is destroyed by melting due to theeffect of the thermal energy. A part of the thermal energy can come fromthe light beam.

Deformation or destruction of the mirror used for ignition of apyrotechnic element enables this mirror to be removed from the initialpath of the light beam F. Thus, during the next ignition period, thismirror no longer prevents the light beam F from reaching the next mirrordesigned to direct the light energy onto the next pyrotechnic element.If the thermal energy destroying the mirror 33 is supplied essentiallyby the light beam, the emission time t₀-t₄ of the laser (FIG. 13) mustbe such that the mirror concerned is removed before the time t₄ withoutthe time separating the time when the mirror is removed and the end ofemission of the laser being sufficiently long to cause ignition of thenext pyrotechnic element.

When the temperature causes melting of the reflecting layer, the lattermust be achieved on a transparent support letting the light beam F passafter the mirror has been removed.

In an alternative embodiment, each mirror is arranged on a support whichis destroyed or deformed by the thermal energy after the ignition periodso as to remove the mirror from the path of the light beam F. An exampleof this type is illustrated in FIG. 12. Each mirror 33 is formed by athin reflecting layer 34 deposited on a support formed by a wafer 35.The wafer 35 is arranged on a wettable surface 36 and on an adjacentnon-wettable surface 37, on a base support 36. The configuration of theassembly is such that the reflecting layer 34 forms an angle of 45° withthe light beam to reflect the latter in the direction of thecorresponding pyrotechnic element. The wafer 34 is made of a materialwith a low melting point that deforms when its temperature reaches apreset temperature. The mirror support is represented in the left-handpart of FIG. 12 after deformation. In this embodiment, the temperatureincrease caused by the light beam has, in similar manner to deformationof the wafers 22 and 31 of FIGS. 4 and 10, led to formation of a pellet39 situated on the wettable surface 36 only. The reflecting layer 34supported by the external surface of the wafer has been simultaneouslydeformed and is no longer located on the path of the light beam F. Thenon-wettable surface 37 and the base support 38 may be made oftransparent materials letting the light beam F pass after deformation ofthe wafer 35.

In a particular embodiment of a device according to FIG. 11, illustratedin FIGS. 15 and 16, the light beam F reflected by a mirror 33 isdirected towards a reflecting element 41 designed to direct it towardsthe associated pyrotechnic element E_(i). In this embodiment, a singlesupport 42 bears the mirrors 33 and the pyrotechnic elements achieved inthe form of layers of pyrotechnic material deposited on the support 42.The reflecting element 41 illustrated in FIG. 15 appreciably has theshape of a trough presenting two opposite inside walls, inclined at 45°,turned towards the support 42 and both covered with a reflecting layer,thus forming first and second mirrors 43 and 44. A light beam reflectedby a mirror 33 is directed vertically upwards in FIG. 15 towards a firstmirror 43, which reflects it, horizontally in FIG. 15, in the directionof the second mirror 44. The latter returns the beam, verticallydownwards in FIG. 15, in the direction of the associated pyrotechnicelement so as to cause ignition of the latter.

An alternative embodiment of mirror supports of a device according toFIGS. 15 and 16 is illustrated in FIGS. 17 and 18. According to thisalternative embodiment, a layer 45 of pyrotechnic material is depositedon a transparent support element 46 of a mirror 33. The mirror 33 isthen formed by a thin reflecting layer deposited on the layer 45 ofpyrotechnic material. The latter is in contact with the layer ofpyrotechnic material constituting the associated pyrotechnic elementE_(i), of which it constitutes a continuation. In this way, ignition ofthe pyrotechnic element also causes combustion of the layer 45 anddisappearance of the associated mirror 33.

FIGS. 19 and 20 illustrate another alternative embodiment of mirrorsupports of a device according to FIGS. 15 and 16 using a shape memoryalloy. An intermediate support 47 made of deformable material isarranged on the support 42. The pyrotechnic element E_(i), and theassociated mirror 33 are arranged at two opposite ends of theintermediate support 47 and separated by an intermediate zone on whichan element 48 constituted by a shape memory alloy is deposited. Thealloy constituting the element 48 can, in known manner, be nickel-based,titanium-based, or have a base made from certain plastic materials orany other suitable material giving it the properties of a shape memoryalloy. When manufactured, the intermediate support 47 initially takes afirst position, horizontal in FIG. 19, in which it is resting on thesupport 42. Before the device is used, the shape memory element 48 issubjected to stresses and to thermal treatment deforming it and bringingthe intermediate support 47, whereto it is fixedly secured in theintermediate zone, to a second position illustrated in FIG. 20. In thissecond position, the intermediate zone of the intermediate support 47 isdeformed so as to curve upwards, bringing the mirror 33 to a positionwhere it forms an angle of about 45° with the horizontal. The mirror 33is then able to reflect a horizontal light beam coming from the laser32. Combustion of the associated pyrotechnic element causes atemperature increase of the element 48 in particular. When thetemperature of the shape memory alloy reaches the recovery temperatureof the latter, the element 48 reverts to its initial shape moving theintermediate support 47 and the mirror 33 which it supports to theinitial position of FIG. 21. The support 47 of the mirror 33 has thusbeen deformed so as to remove the mirror from the path of the light beamemitted by the laser 32.

The element 48 may constitute the intermediate zone of the intermediatesupport 47.

1. A module for supplying hydrogen to a fuel mini-cell comprising meansfor triggering and controlling gradual release of hydrogen in the fuelmini-cell, the hydrogen being supplied by combustion of a plurality ofpyrotechnic elements integrated in the module, after ignition of saidpyrotechnic elements, said means comprising an energy source and adevice for sequential control of ignition of the pyrotechnic elementscomprising means for selectively connecting the energy source to anignition element of each of the pyrotechnic elements, the connectingmeans comprising means for connecting a single ignition elementassociated with a predetermined pyrotechnic element to the energy sourceduring a preset ignition time, and for automatically preparingconnection of another pyrotechnic element to the energy source after theignition time.
 2. A module according to claim 1, wherein the connectingmeans comprise temperature-sensitive means to prepare connection of anignition element of another pyrotechnic element to the energy source. 3.A module according to claim 2, wherein the temperature-sensitiveconnecting means comprise a material with a low melting point thatdeforms when the temperature reaches a preset value so as to establishan electrical connection between two tracks of an electric circuit.
 4. Amodule according to claim 3, wherein the material with a low meltingpoint is deposited in the form of a wafer on the end of each track so asto form a single trough electrically connecting the tracks when thetemperature reaches a preset value.
 5. A module according to claim 1,wherein the connecting means comprise pressure-sensitive means toprepare connection of an ignition element of another pyrotechnic elementto the energy source.
 6. A module according to claim 5, wherein thepressure-sensitive connecting means element comprise a flexible membranedeformable by the pressure generated by the combustion gases of theassociated pyrotechnic element so as to establish an electricalconnection between two tracks of an electric circuit.
 7. A moduleaccording to claim 2, wherein, the energy source being an electricalenergy source, the connecting means comprise an input terminal and meansfor connecting the input terminal to the energy source during eachignition period, the input terminal being, at any given time, connectedto an ignition element of a single pyrotechnic element, combustion ofsaid pyrotechnic element actuating, after said ignition period,connecting means sensitive to temperature or pressure automaticallycausing connection of the input terminal to an ignition element ofanother pyrotechnic element.
 8. A module according to claim 7, whereinthe ignition elements are heating filaments.
 9. A module according toclaim 8, wherein, in the ignition position, the heating filamentconcerned is connected to the terminals of the electrical energy source,the connecting means sensitive to temperature or pressure constitutingnormally open switches arranged between two adjacent heating filaments,a heating filament being automatically cut off during or at the end ofits ignition period.
 10. A module according to claim 1, wherein theenergy source is a light energy source and the connecting means comprisea plurality of small mirrors successively arranged on the initial pathof a light beam emitted by the light energy source, each mirror beingassociated with a corresponding pyrotechnic element, a light beamemitted by the light energy source being reflected by the first mirrorencountered on its path, in the direction of the correspondingpyrotechnic element, so as to cause ignition of the pyrotechnic elementduring an ignition period, the mirror being removed from said path afterthe ignition period so that a subsequent light beam reaches the nextmirror.
 11. A module according to claim 10, comprising a reflectingelement in the form of a trough designed to direct the light beamreflected by one of the mirrors towards the associated pyrotechnicelement.
 12. A module according to claim 10, wherein the mirror isdeformed or destroyed by the thermal energy received, after ignition ofthe associated pyrotechnic element.
 13. A module according to claim 12,wherein the thermal energy is released by combustion of the associatedpyrotechnic element.
 14. A module according to claim 12, wherein thethermal energy is at least partly supplied by the light beam.
 15. Amodule according to claim 10, wherein each mirror is arranged on asupport that is deformed when the temperature reaches a preset value.16. A module according to claim 15, wherein the mirror support comprisesan element formed by a shape memory alloy.
 17. A module according toclaim 10, wherein the energy source is a laser.
 18. A module accordingto claim 10, wherein the mirrors are achieved in the form of thinreflecting layers.
 19. A module according to claim 1, wherein the moduleis contained in a card.